Start of main content
Check if array has duplicates
JavaScript, Array · Oct 22, 2020
Checks if there are duplicate values in a flat array.
- Use
Setto get the unique values in the array. - Use
Set.prototype.sizeandArray.prototype.lengthto check if the count of the unique values is the same as elements in the original array.
const hasDuplicates = arr => new Set(arr).size !== arr.length;hasDuplicates([0, 1, 1, 2]); // true
hasDuplicates([0, 1, 2, 3]); // falseMore like this
Check if array has many matches
JavaScript, Array
Checks if an array has more than one value matching the given function.
Check if array has only one match
JavaScript, Array
Checks if an array has only one value matching the given function.
Array symmetric difference
JavaScript, Array
Returns the symmetric difference between two arrays, without filtering out duplicate values.